1. Field of the Invention
The invention relates to: expandable tubulars for use in geologic structures, such as for use in the production of hydrocarbons, such as oil and gas, or oil field tubulars, and for use in similar wells and structures, such as water wells, monitoring and remediation wells, tunnels and pipelines; methods for expanding oil field tubulars and other expandable tubulars; and methods for manufacturing expandable tubulars. Expandable tubulars include, but are not limited to, such products as liners, liner hangers, sand control screens, packers, and isolation sleeves, all of which are generally used in geologic structures, such as in the production of hydrocarbons and are expanded outwardly into contact with either the well bore or the well casing, as well as products for use in similar wells and structures, as previously set forth.
2. Information Incorporated by Reference
Applicant incorporates herein by reference U.S. Pat. Nos. 5,785,122; 6,089,316; and 6,298,914, each entitled “Wire Wrapped Well Screen”, and commonly owned by the applicant herein.
3. Description of the Related Art
Drilling and construction of oil and gas wells remains a slow, dangerous, and very expensive process despite a century of continual technological advances. With the costs of some wells approaching 100 million dollars, the primary cause of these high costs occurs due to the need to suspend drilling progress in order to repair geologically-related problem sections in wells.
The major problems of lost-circulation, borehole instability, and well pressure control are still generally rectified only by costly and time-consuming casing and cementing operations. Such conventional sealing processes are required at each problem-instance, often dictating installation of a series of several diametrically descending, or telescopic-casing strings in most wells. Generally, each casing string is installed from the surface to each problem zone and a 10,000 foot deep well often requires 20,000-30,000 feet of tubulars.
Disadvantages of telescoping practices are numerous, including the requirements of excess excavation work and corresponding equipment requirements for over-size rock borings and their over-production of costly waste products. Beginning diameters in excess of 24″ are usually required to allow a 5″ or less final production string. Large-scale drilling operations currently may require drilling equipment hoist ratings as high as 2,000,000 pounds and consume several acres for drill-site location, with both requirements due largely to various casing needs and operations. Frequently, and despite major expenditures and efforts, the final telescope casing size, or production string, may be too small to economically produce the hydrocarbon resource, resulting in a failed well.
The energy industry has pursued development of alternative, “monobore” well-casing systems in recent years, wherein one size casing is used from the surface to the target zone, normally some 1-7 miles below. Monobore concepts replace each former concentric surface-to-problem-zone casing string installation with discrete-zone placement of an expandable casing. A median casing size of 7⅝″ outside-diameter (“OD”) would ideally be expanded to approximately conform to a nominal 10″ borehole by means of a cold-work, mechanical steel deformation process performed in-situ. The expanded casing assembly must meet certain strength requirements and allow passage of subsequent 7⅝″ OD casing strings as drilling deepens and new problem zones are encountered.
The foregoing deforming process inherently requires use of soft steels, which cannot produce many critical mechanical properties required in high-demand environments normal to oil and gas wells. It is believed 60-70% of potential customers cannot consider using current expandables due to fundamentally unsolvable technical issues. The deformed casing provides no sealing effect, and thus, cementing operations are still required.
A variety of downhole expandable tubulars and downhole “tools” are presently in use for oil and gas production. The ultimate success of these new expandable tubulars and/or downhole tools will be dependent upon their ability to comply, or adhere, to the various subsurface geometries against which they are expanded, and their use to create some control over well bore fluid flows. Subsurface conditions continually change over the life of any type of well due to abrasive wear of formation particles, subsidence or various biological, chemical and geo-chemical processes occurring over years. Those expandable tubulars, after having been expanded must substantially retain their compliance throughout their useful life.
True expandable tubular, or device, compliance cannot be accomplished with current, expandable tubulars due initially to the natural tendency of steel materials to “spring back” from their altered states to their natural, or original, form. Spring back is also sometimes referred to as “recovery”, “resilience”, “elastic recovery”, “elastic hysteresis”, and/or “dynamic creep”. The principle exists in all stages of worked steels, or other metallic materials, until the point of rupture, due to excess deformity. For pre-ruptured tubes, there are different degrees of deformity throughout the thickness of the tube-arc, translating to guaranteed springback, at rates varying according to the severity of arc, corresponding to severity of deformation. Of course, “spring back” is greater if the metallic material, such as steel, has not been deformed beyond the elastic limit of the material.
Current expansion methods and expandable devices are capable only of deforming material according to one vector and assume device-freedom, or no obstructions or additional work requirements such as pressure against well bore rock. Indeed, local expansion essentially ceases upon encountering such a work obstacle; and the expansion can likely never be 100% adherent. Expansion essentially stops upon encountering the obstruction, or rock, and the expandable tubular then shrinks, and an annular space typically always exists with current technologies.
It is primarily localized over-expansion and excess material deformation, abutting the imperfections which are quite common in any well bore or cased hole environment, which create any type of device, or tubular, well bond; however, the expanded device and well formation are not substantially adhered to one another. The problem is compounded with expansion occurring in irregular geometry environs. Since upon final expansion, the device is static, absent its tendency toward recovery, or spring back, and any work imposed on it by the well bore environ, problems may be caused by compliance-voids, or uncontrolled “hot-spots” of high-velocity and high-pressure fluid flows in the well.
The purpose of expandable tubulars is to permit a “solid-tubular”, such as a casing, liner-hanger, isolation sleeve, packer and/or sand-control screen to be passed through the smallest diameter casing and/or borehole in a well for the production of hydrocarbons, and then be subsequently expanded against that casing or directly expanded against a larger uncased borehole. An important economic benefit is that the expense and time to install cement or gravel pack envelopes are eliminated, or greatly reduced.
For sand-control screens, the technical benefits begin with improved wellscreen-borehole proximity, as well fluids are less inhibited to enter the screen. Further benefits may include improved access and mechanical effectiveness for removing drilling mud, repairing drill damage, and restoring natural production potential. Additionally, greater functional screen-surface-area is produced which provides more functional fluid-flow area and plugging resistance. Another benefit created by wellscreen expansion is greater internal diameter of the expandable tublular. This allows for placement of larger diameter pumps and other equipment or tooling into the producing areas of a well, which are in use in various available “intelligent well” flow-control hardware, such as pumps, valving and in situ separators.
In general, presently available expandable tubulars, and methods for expanding them, utilize a perforated or slotted basepipe, or original tubular member, which is expanded, or deformed beyond the elastic limit of the material forming the basepipe, or plastically deformed, by forcing an expansion device, such as a pig or a mandrel through the basepipe and expanding and deforming it, or by pulling through, or rotating within the basepipe, tapered wedges or rollers, to again expand and permanently deform the basepipe. It is believed that presently used expandable tubulars have a capability of having their outer diameter expanded by a factor of from 25 to 50 percent, whereas it is believed that an increase of one hundred percent would be desirable. Another disadvantage of presently available expandable tubulars is the reliability of the expansion. Reliability problems stem from the complexity of the devices themselves, wherein several layer-elements are required to act in coordination with each other with some presently known expandable tubulars. Irregularities in borehole conditions, including excess bend severity, swelling induced diameter restrictions, and non-concentricity, may each tend to prevent these coordination requirements.
Another disadvantage of presently used expandable tubulars, relates to their limited collapse resistance. The expansion and permanent deformation of currently available basepipes, inherently results in a progressively thinning outer wall thickness. For collapse resistance, greater wall thickness is required as the diameter of the tubular expandable, or device, increases. Some present products provide for as little as 270 psi collapse resistance at full expansion, while others may provide approximately 1000 psi collapse resistance. The industry preference would be approximately 3500 psi minimum. Thinning of a conventional expandable tubular occurs rapidly as its diameter is increased. It is also well known that high-levels of deformity cause stress-cracking and a variety of metallurgical problems. The deformed-device resistance to collapse forces is lost at a certain rate proportional to the cube of its outside diameter. It is believed that the loss of collapse resistance is accelerated by the use of slotted basepipes, which actually result in substantial areas void of any steel mass. While employing thicker walled basepipes might represent a solution to collapse resistance problem, a robust wall thickness requires significant additional mechanical work in order to be expanded. The additional work is, in turn, believed to be beyond the capabilities of current expansion devices, costs, and competitive field time requirements. Furthermore, an expansion process too robust can create additional void areas in some geology and well materials.
Another disadvantage is general compliance, in that only perfect conditions are addressed conventionally, but very few aspects of downhole geometrical conditions are perfect. This is true, particularly, with regard to roundness, as it is generally a required condition for effectiveness of conventional technologies. Even cased-hole environments exist only as varying degrees of eccentricity or ellipticity, not generally with perfect roundness. Potential uncased borehole geometry is unlimited. It is believed that conventional expandable tubulars cannot be suitably utilized in non-round conditions, as these conditions compound all collapse stresses exponentially to already inversely-cubed-variables found in Timoshenko and similar plates and shells formulae.
A further disadvantage of conventional expandable tubulars is the lack of true-compliance in the form of expansion-energy storage and dynamic adjustment capabilities. Currently, no mechanism has been provided to maximize adherence of an expanded, expandable tubular device due to: the energy dampening effects created through deformity of ductile materials; inefficient energy transfer through multiple layers of some expandable tubulars; and “spring-back” principles inherent to any material phase. Additionally, the expansion and deformation of soft, ductile basepipe materials beyond their elastic/plastic limits may create well-known stress-cracking issues.
A further disadvantage of present, conventional expandable tubulars, is that as the basepipe, or originally utilized tubular member, is deformed outwardly into engagement with the well bore, such outward radial expansion causes the overall length of the tubular member to be shortened. Such shrinkage, along the longitudinal axis of the tubular member, can impede radial expansion when casing between casing “stuck points” and present spacing and connection problems when joining multiple sections of basepipe within a borehole, as axially spaced voids of varying length may be present, dependent upon how much radial expansion of the basepipe has occurred, which results in the undesired axial shortening of the basepipe.